Full Program »

Interpretation of the mechanism responsible for the persistence of a laminar region in turbulent duct flow

PDF
0.2MB

The flow field in an isosceles triangular duct with a small apex angle of 11.5 degree is investigated using direct numerical simulation at the hydraulic Reynolds number Reh = 4500. Within the duct cross-section regions with essential laminar and turbulent properties are found to exist next to each other. From analysis of this flow field we gain insights into the mechanisms responsible for the flow laminarisation towards the corner of the duct, which leads to a significant reduction of the skin friction. In addition, further
investigations of the disturbances appearing in the laminar part of the flow domain indicate a possible application of corners for the delay of laminar to turbulent transition in duct flows.

Author(s):

Gerti Daschiel    
Institute of fluid mechanics, Karlsruhe institute of technology
Germany

Bettina Frohnapfel    
Institute of fluid mechanics, Karlsruhe institute of technology
Germany

Jovan Jovanovic    
Institute of fluid mechanics, University of Erlangen-Nürnberg
Germany